Tutorials

I have been busy designing a Medieval Bridge,and it will have eight or ten complex parts,and each will be cast up separately. These will make up a single arched bridge,a double arched bridge,or even more arches if required.

Each mould will produce stone work for each side of the bridge. Others will form the inner arch ways and their stone work. Some will make up the top of the bridge and its stone wall and path and road way,_____________________but first the Sample, just to see if my idea will work. Wish Me Luck

Yip! A Poor Mans Polystyrene Pattern & Box held together with pins and Sellotape. The Filling Plaster of Paris! The purpose? To produce a tuff reusable open topped Mould.

The Rubber Casting made using these ingredients.Silicone,Cornflour,Baby Powder and Baby Oil.

This Rubber Casting was produced with left over stuff from another project that is ongoing,and as can be seen it can produce many more. It is hoped this could be a useful help to others in the hobby. BB

Below The Next Set of Patterns They were stuck onto an offcut of card saved especially for this purpose, and this stopped them from moving while the Plaster of Paris was poured over them.

Once again a very cheap but fit for purpose Box was made,but before the pour I reinforced the edges with supporting off cuts ,and sealed the edges with Sellotape like before on the Sample Box.

It took one complete small jug full to fill the open top mould. Over each Pattern the Plaster of Paris was aggertated up and down in a dabbing motion using a cheap paint brush, and in this way it avoided air bubbles spoiling the work.

Yes,I do realise it looks like an iced over cake!

The Mould was turned over, and the Patterns came out really easy.It is hoped that I can do more elaborate complex works in the near future,but for now this is a simple learning curb )

What I am doing is what I would term, Reverse Model Making, because usually the mould is made of Rubber and the Casting made of Plaster Resin. Now with this differing process if the casting is dropped or even thrown across the room hitting the wall even,it will not break into a thousand pieces.I`ll cast these parts up soon,and good or otherwise I will show the results. One thing I would like to mention is the Silicone Rubber Mix can have colour of choice added to it when Mixing the stuff up. I am now working on some more Patterns that will make up more parts needed. BB

It Looks good... The one Problem I can see is that the mould, being made of plaster, will wear away as it´s used and the Details will be less and less defined as each new Piece is cast. I can (maybe) see why plaster is a choice for the mould..the polystyrene master would stick to silicone/rubber but ...Theoretically..the first cast could be coated with something, varnish or whatever, then it becomes the master and a silicone/rubber mold made from that?

Thank you guys for your interest & questions. I will put another head on and do my upmost to answer them.

I must admit Paul you have raised a good point to concider,and it is one I pondered on too. That's why I added a little something extra to the Plaster of Paris Mix. A Secret Passed on by Word of Mouth in the Beano Family! The Moulds were left to dry out for many days until Rock Hard. The longer one leaves this stuff the Harder it will get,almost like Ancient Concrete,but not heavy,and the Moulds and what they produce are Waterproof too. When cured the casting,or infact a better description The Pressing once lifted slightly with a craft knife just peels off and out nicely without any tug or pull to the actual mould.You guys are right,It is also possible to take an impression of the Mould completely in the same mix Silicone Rubber,and cast in plaster which on tiny casting is OK,but would break if dropped. Dalibor the main reason why the Silicone Rubber Mix , is once the flat inner stone work has cured it will bend into shape when the Arches are created. Whereas a plaster casting would not. The same applies with the roadway over the bridge,because I can have complete flat castings made that will bend into shape over the Bridge.

Below. Proof of the Bending

Inspite of all the bending it flips back and stays in shape .

I also intend to make Railway Tunnel Entrances in much the same way,and stone work and rock faces that will bend into the shape that I wish,and which will be stuck in place using Silicone HA6 Adhesive,much the same way as this project will be. Well I know it will stick,it`s made of the stuff. Simple wood supports inside each end ,and in the middle of the Bridge will make it easy to construct. I Hope!

I have many expensive moulding materials that I could use, but I want this to be the cheapest easiest way of making moulds that would inturn produce fine castings that are well fit for my purpose. If Hat Industries can produce such stuff I thought that I would take a leaf out of their book and do the same.

This Two Part Mould on the right hand side of the picture,was made with the same Silicone HA6 Mix already described,and it being much thicker is still flexible so the casting will just pop out with ease,it is also very tuff. This will be cast in Plaster of Paris and Dental Porcelain Powder Mix.

Well it`s the first of June,and here in Fiddle Wood ,things are starting to take shape.

Below the underneath of another mould that has been cast in the same way as the others.

This is the mould of the roadway that will produce flexible flat castings that will simply bend into the required shape of the bridge. Easily cut and trim to required lengths It will also bend forming the inside of the arches too. So this will be quite a multipurpose mould.

The first castings having been peeled easily from their moulds. They were painted and have been given a dark wash! When I make the rubber up to cast the roadway the other side of the bridge will also be made ,so that there will be very little waste.The little fellow sets the scale at 20mm which is 1/76 Railway Scale. BB

I called this part.Reflections,like in a river,because I`ve been trimming each side to be the same. So I know they will form each lower section of the stone bridge and will be spot on target when the construction starts. Where the pieces meet in the middle of the upper archway there will be other stone work set in place which will be made of rubber too.

The 1foot by 3 inch rubber stone roadway that doubles up to form the arches too has been a complete success. I`ve already made two sections up and painted them white, then a dark wash was applied for this illustration.

As I have been doing other stuff with rubber, what was left over formed road the lower parts of the bridge. So nothing was wasted. Work designing the upper bridgework of flint stone and render has begun so I hope to include that here ASP! BB

Not much to show really,but work is still sort of ongoing at odd times on this project and the journey to completion.

This small bridge is just right in size to allow Narrow Boats through without having to tip their chimney pots over,like on the real boats.

The two lower sides of the bridge have been constructed as planned and they presently meet in the middle and so are not fixed together. The roadway of stone sets has not been fixed.It has just for this photo shot illustration been laid loose across the bridge.

So five sections of bridge parts make up this picture,and as you can see plenty of head room on this tiny HO OO Railway Scale. There will be minor alterations made,but nothing to demanding and that's the great thing about scratch building I like. One is always on a learning curb of bright beaming adventure_____and along the way you get to make Mess,which is Great. O`no Mrs B,I`ll clear it up later. The upper sections of the bridge walls can now be cast.

Working on other more important stuff,has ment a delay on this project,but I`ll get there in the end. When is another question I cannot answer.

However I always finish the object as close to neatness as I can, As for myself I`m always neat too,In my untidy state of artisan passion for the craft. BB